Quadruple witching day

Financial markets Friday are braced for “quadruple witching day.” That’s one of those rare occurrences that can send share prices on wild rides – and can send investors scrambling for a dictionary of finance.
Officially, quadruple witching occurs when expirations hit for two types of option contracts (stocks and stock indexes) and two types of futures contracts (stock indexes and single stock futures).
Don’t ask where the scary name comes from. If you’re curious, though, someone has written about the use of “haunted” language by investors.
What’s important is that these witching days come on the third Friday of March, June, September, and December.
The confluence of expirations can mean high trading volume and some extra volatility for individual stocks, as investors buy or sell shares to cover their contracts – often near the end of the day.
But it doesn’t necessarily lead to a big swing in indexes like the Standard & Poor’s 500.
Consider the last two “witching” days: March 20 and June 19. In March, the Standard & Poor’s 500 index fell nearly 2 percent on Quadruple Friday, closing at 768.54. That qualifies as a big-swing day, even in a year with some large one-day moves.